AM fungi might affect the root morphology of maize by increasing indole‐3‐butyric acid biosynthesis

Abstract

mycorrhizal maize roots could be mimicked by IBA applied Inoculation of maize (Zea mays L.) with the arbuscular mycorrhizal (AM) fungus Glomus intraradices resulted in a exogenously to non-mycorrhizal roots. Addition of trifluorodistinct root phenotype ca 10 days after inoculation. Al-IBA (TFIBA), an inhibitor of IBA-induced root growth and lateral root induction, simultaneously with IBA resulted in a though the fresh weight of inoculated and control roots was phenotype resembling that of untreated controls. In roots about the same, the AM-inoculated roots showed a signifitreated with TFIBA the inoculation with AM fungi did not cant increase in the percentage of lateral fine roots. This increase the formation of fine roots. The TFIBA treatment increase coincided with an increase in free indole-3-butyric acid (IBA) as well as an increase in IBA synthesis. At later also reduced endogenous free IBA and the AM infection rate time points (31 days after inoculation), the free IBA content in mycorrhizal roots. The results are discussed with respect was not increased in infected roots; however, the fraction of to a possible role of IBA in the establishment of AM symbiosis. bound IBA increased compared to controls. The phenotype of are involved in signalling events between AM fungi and host plants. The levels of phytohormones in maize colonized with a Glomus isolate were analysed by ELISA and conventional bioassays (Danneberg et al. 1992, Esch et al. 1994. Measurements of abscisic acid (ABA) showed considerably higher levels of ABA in AM-colonized than in control roots, whereas the concentrations of zeatin riboside (with the exception of later stages of AM development) and indole-3acetic acid (IAA) were similar for infected and non-infected roots (Danneberg et al. 1992). The concentration of ABA in hyphae of Glomus was at least one order of magnitude higher than that in maize roots without AM fungi (Esch et al. 1994). The authors concluded that Glomus is able to contribute to the increase in ABA in the infected roots.Since stable isotope labelled standards became available for the determination of plant hormones, it is possible to measure accurately auxin levels using gas chromatographymass spectrometry (Cohen et al. 1986, Sutter and Cohen

Arbuscular mycorrhizae modify winter wheat root morphology and alleviate phosphorus deficit stress

“…These results indicate a positive effect of AM on root branching. A similar effect of AM on root branching was also described in maize (Zea mays L.) (Kaldorf and Ludwig-Müller 2000) and trifoliate orange (Poncirus trifoliata L. Raf.)…”

Indole-3-acetic acid: A widespread physiological code in interactions of fungi with other organisms

“…65 Auxin derivatives such as IAA and IBA (Indole-3-butyric acid) promote the development of lateral roots, which are the preferred infection sites for the AM fungi. 66,67 Transgenic tobacco plants expressing the b-glucuronidase (GUS) reporter gene fused to an auxin-inducible promoter showed increased auxin levels in roots colonized by AM fungi. 68 Similarly, DR5::GUS, an auxin response reporter, was induced in arbuscule-containing root cells in tomato plants.…”

Arsitektur akar bibit kelapa sawit yang diinokulasi beberapa cendawan mikoriza arbuskula Root architecture of oil palm seedling inoculated with selected arbuscular mycorrhizal fungi

“…Peningkatan sistem perakaran dengan inokulasi CMA juga dilaporkan Berta et al (1990) pada Allium porrum, Fitter (1986) pada Trifolium pratense, dan Hooker et al (1992) pada poplar. Perubahan sistem perakaran kemungkinan disebabkan perbaikan hara tanaman dan induksi pembentukan hormon tanaman (Kaldorf & Muller, 2000).…”

“…Selain itu, ditunjukkan bahwa kisaran diameter akar tersier meningkat dengan inokulasi dan inokulasi mempercepat pembentukan akar tersier (Tabel 3). Perubahan morfologi yang terjadi khususnya pada pengaruh inokulasi kemungkinan disebabkan perubahan kandungan hara atau hormon seperti dikemukakan Kaldorf & Muller (2000). Selain itu, inokulasi dapat mempercepat pembentukan akar kuartier.…”